Cárdenas, C., Plaza, A., & Baños, J. 2007, May 29–June 1, TTCN-3 Test System for Automotive Emergency Call Service. Unpublished paper presented at ETSI TTCN-3 User Conference 2007, Stockholm (Sweden).
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|Resource type: Conference Paper
BibTeX citation key: Cardenasa
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Creators: Baños, Cárdenas, Plaza
Publisher: Ericsson, ETSI (Stockholm (Sweden))
Collection: ETSI TTCN-3 User Conference 2007
Road accidents are one of the most important causes of European citizen death. The European Union by promoting R&D projects intends to foster innovation that may lead to decrease the number of road casualties. New wireless technologies providing features such as more range, higher data rate and reliability, are appearing to stand for the development of road safety traffic services and systems. Currently, two lines of development are being followed by EU: preventive systems and post accident systems. Ones are conceived to minimize the possibility of accidents by allowing drivers to extend theirs line-sight through the use of wireless communications. Others are conceived to reduce the time-to-rescue once accident occurs. In this scenario, interoperability among the actors is a need that has to be assured.
There are a high variety of car manufacturers and road infrastructures providers and thus their devices should be in compliance with the system specification and interoperability with each other. Furthermore, since the strategic mission of these systems is to avoid casualties, it is imperative to deploy a completely reliable road traffic system.
One of the main applications specified for this purpose is called Emergency Call (eCall) whose scope is to send a data message (containing its geographical position, plate number, information about the vehicle, and so on) and to establish an emergency voice call with a PSAP (Public Safety Answer Point) when a vehicle has a road accident. PSAP is responsible for assessing the optimal route and ordering emergency vehicles to drive toward the accident place. The underlying technology selected as means of communication transport has been GSM whereas USSD is the service selected to send the application messages. At present, ETSI and 3GPP are including emergency services as inherent services in Next Generation Network (NGN).
One of the key challenges of the work is that the resulting heterogeneous networks are changeable and evolutionary. For example, UMTS technology may be selected as mean of transport between the vehicle and the PSAP rather than GSM technology. On account of these issues, TTCN-3 is the most adequate formal language to develop eCall test specifications because it is platform independent and will facilitate the evolution of a test tool based on TTCN. AT4 wireless as a GST/CERTECS partner has developed a complete Conformance Test System for Emergency Call based on TTCN-3.
The Emergency Call Test System includes all the test cases edited in TTCN- 3 and all the modules which compose the TTCN-3 Test System with “C” as core language.
The System Adaptor (SA) module of the test system is in charge of controlling a GSM Signalling Unit (external hardware implementing GSM protocol stack). Thus, this architecture allows keeping the TTCN-3 test suite and only modifying the SA module in case of latter evolution of another underlying technology such as UMTS or WiMAX. The Platform Adaptor (PA) module mainly implements the external functions to configure the behavior of the GSM Signalling Unit.
Another highlight of this development is the CODECS module. For Emergency Call the data messages are encapsulated in a USSD message, and these are encoded and decoded through a set of encoding and decoding algorithms. Since theses algorithms have been already implemented on Java language by system prototypes (in the scope of GST) and in order not to make redundant effort by implementing them again, the CODECS module uses directly these implementations by means of JNI technology which enable developers to invoke Java code from applications developed in C languages.
The test tool developed in AT4 wireless acts as Test Management module providing an easy and friendly GUI (Graphical User Interface) to manage all the test procedure. Finally, the Test System has been validated successfully against some eCall samples from different GST partners.
The paper will present the implementation and validation of an eCall Test System based on TTCN-3 and conceived for testing safety vehicle applications over heterogeneous networks. Moreover, some challenges and experiences which appeared during this work will be presented.
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